Apparatus for casting stereotype printing plates



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APPARATUS 'FOR CASTING STREOTYPE PRINTING PLATES Filed March 26. 1956 yI 6 Sheets-Sheet 5 JUZ Ply/V65? CLOSE To Ls To L51 Z July 21, 1959 c. w.CHASE ETAL 2,895,187

APPARATUS FOR CASTING STEREOTYPE PRINTING PLATES Filed March ze, 195e esheets-sheet e Jja.

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United States Patent O APPARATUS FOR CASTING STEREOTYPE PRINTING PLATESCorson Walter Chase, Oak Park, and Glenn Nicholas Krueger, NorthRiverside, Ill., assignors to Miehle- Goss-Dexter, Incorporated,Wilmington, Del., a corporation of Delaware Application March 26, 1956,Serial No. 573,904

12 Claims. (Cl. 22-2) This invention pertains in general to apparatusfor casting curved stereotype printing plates and, in particular, tosuch apparatus having a stationary, concave mold box and a convexplunger movable relative thereto to form a mold space and to aifordconvenient removal of the cast plates. Y

The general aim of the invention is to bring about a very muchsimplified, rugged, and inexpensive construction for such plate castingapparatus which, nevertheless, is faster and more reliable in itsoperation.

Coordinate with that aim, it is an object of the invention to do awaycompletely with an individually movable head ring, and the actuatinglinkage therefor, heretofore deemed necessary to close the bottom of themold space formed between the mold box and plunger, therebysubstantially eliminating the possibility of tins or ashings on castplates.

A related object of the invention is the realization of an arrangementin which the bottom of the mold space is closed by a head ring integralor rigid with the plunger itself and which may be constructed to createa beveled bottom edge on the cast plates.

Concurrently, it is an object of the invention to provide a head ringwhich effects a more uniform and precisely controlled spacing betweenthe mold box and plunger when the latter is in its closed position, tothe end that successively cast plates are more uniform in thickness.

A related object is the provision of a head ring integral or rigid withthe plunger and so constructed as to avoid overheating of the formerwhen plates are cast in rapid succession.

Another object of the invention is to provide a linkage for moving theplunger in a manner such that a head ring rigid therewith clears themold box during movement, but properly seats against the latter when theplunger is fully closed.

Still another object of the invention is to provide such an arrangementin which the head ring clamps a type matrix in the mold box when theplunger is closed, but does not slide or rub along the matrix before thelatter is stripped from a cast plate. By this provision, the inventioncontemplates apparatus including matrix setting and stripping meansautomatically actuated as the plunger opens and closes in such a waythat the matrix is not torn, wrinkled or otherwise damaged, thuspermitting the same matrix to produce several cast plates in succession.

It is a further object of the invention to make possible the strippingof a cast plate from the plunger as the latter swings `to a horizontalposition even though a recessed head ring rigid with the plungerprevents movement of the plate directly transaxially of the plunger.

Still another object of the invention is to construct a plunger so thatit creates circumferential ribs on the undersides of cast plates, yetsuch that the cast plates may be stripped from the plunger with otherthan a direct transaxial motion.

g '2,895,187 Patented July 21, 1959 An additional object of theinvention is to reduce the physical effort required to move the plungerbetween its closed and open positions by the use of power meanscontrolled to prevent slamming of parts and to provide a constantpressure to hold the plunger in closed position.

Other objects and advantages will become apparent as the followingdescription proceeds, taken in conjunction with the accompanyingdrawings, in which:

Figure l is a side elevation of plate casting apparatus embodying thefeatures of the invention;

Fig. 2 is a plan view of the apparatus shown in Fig. 1;

Fig. 3 is an end elevation, partially in section, taken substantiallyalong the line 3 3 in Fig. l;

Fig. 4 is a fragmentary vertical section through the mold box andplunger with the latter in its closed position;

Figs. 5 and 6 are plan views of the mold box with the plunger in itsopen and closed positions, respectively, particularly illustrating theconstruction and operation of automatic mat-setting means;

Fig. 7 is a diagrammatic side view of the mold box and plunger showingthe motion imparted to the latterv by its movable linkage.

Figs. 8, 9 and l0 are diagrammatic stop motion views showing the plungerin its closed, partially open, and fully open positions, respectively,and particularly illustrating the operation of the plate-strippingmeans.

Fig. 1l is a diagrammatic illustration of a power Referring now to thedrawings, it will be Ihelpful rst,

by way of setting the environment of the invention, to observe the majorcomponents of, and their functions in, plate casting apparatus of thetype with which the invention is concerned. In general terms, theapparatus includes a stationary mold box 15 and a movable plunger 16,the latter being movably supported on two spaced frame members 18extending forwardly from the mold box. The plunger is adapted to swingbetween a. vertical or closed position With respect to the box 15 and ahorizontal or open position (compare Figs. 8 and 10). In its closedposition (Figs. 5 and 7) the plunger defines with the box a curved moldspace 19 open at the top to receive molten type metal. Seated againstthe box within the mold space is a type matrix 20 which creates typeimages or impressions on the convex surface of the curved plate when itis cast. When the plunger 16 is then moved to its open, horizontalposition, the cast plate P is carried with it and swung to a horizontalposition where it may be conveniently shifted into finishing apparatus(not shown) for shaving and trimming.

The mold box 15 is a relatively large, stationary, upright member havinga concave surface 21 on its front side, the interior of the boxcontaining uid passages or conduits for the circulation of coolantswhich carry away the heat of molten metal poured into the mold space.For the purpose of holding the exible matrix 20 rmly seated against theconcave surface 21, the mold box 15 also has a vacuum manifold 22adapted for connection to a suitable vacuum source (not shown) andleading to surface 21.

Because of the advantageous features afforded by the present invention,the mold box 15 may successfully be equipped with automatic mat-settingmeans, i.e., holders for flexible mats made of papier-mch, for example,which seats the mat against the surface 21 as the plunger is closed andholds the mat as the plunger pulls away during initial opening movement.As shown best in Figs. vand 6, aV mat-setting leaf 25 is disposed oneither side of the concave surface 21 and pivoted to rock about avertical axis by connection to a vertical pin 26. These leaves` extendover substantially the entire height of the mold box and are biasedoutwardly therefrom by torsion springs 2S (Fig. 6). For clamping thevertical edge of the mat 20; each mat-setting leaf 25 carries a slidablejaw 29 which may be opened and closed, for example, by la handle 29a toclamp the mat at its edge portions 20a. With the mat thus held to theleaves 25 by the jaws 29, it is moved between a forward position (Fig.6) and a rearwardposition (Fig. 5) where it is held against the surface21 by vacuum applied through the ports 24. The mat-setting leaves 25,are deflected against the force of their biasing springs 28 to theclosed position illustrated by Fig. 5 as an incident to movement of theplunger 16 into the box Y `as will be explained in more detail be- Asshown best in Figs. 2 and 3, the two side frames 18 areY quite simple inorganization. Each forms a support resting on the floor and is bolted asat 30 to one side of the mold box 15, extending forwardly from thelatter substantially vertical plane. On its upper edge, each of theframes 18 is shaped to define a guide rail 18a which may be of invertedV-shape. This guide rail 18a forms the principal support for the movableplunger 16 as will be explained below.

The plunger 16, sometimes called the core, is a large metal part havinga convex surfaceZ, substantially semicylindrical, adapted to fit intothe concave surface 21 off'the mold box 15. With this, the mold space 19(Fig. 5) becomes substantially semi-cylindrical so that the cast platesare curved and fit readily on the cylinders of rotary printing pressesof the type used in printing newspapers and magazines. The interior ofthe plunger 16 may be formed with passages for the circulation of liquidcoolants, asis Well known. Along the edges of the outer or flat face ofthe plunger are fastened a pair of sliding bar brackets 34. Thesebrackets may be suitably bolted di- Iectly tothe plunger' and carry apair of sliding bars 35 whichY may be moved radially of the plungerafter the latterris in its closed position to seal off the front edgesof the mold space 19. Since the details `of the construction andactuation of the sliding bars 35 are well known inthe art, those detailshave not been illustrated here and need not be more fully described.

As explained previously, the plunger 16 is supported on the frame sides18 such that i-t may be shifted toward and away from the mold box 15,and at the same time be tilted between a vertical and a horizontalposition. Carried on the sides of the plunger are a set of four mat leafactuators which may take the form of blocks 37 bolted to brackets 34. Asthe plunger swings to its vertical, closed position, therefore, theblocks 37 will strike the mat-setting leaves 25 and shift them inwardlyagainst the bias of the torsion springs 28, so that the mat 20 held bythe leaves is moved back against the concave Ysurface 21 where it isretained by suction against the ports 24. Y

ln accordance with the present invention, the bottom of the mold space19 is closed by a head ring 4t) rigid or integral with the plungeritself, As here shown, the head ring is semi-circular in shape and heldtightly to the underside of the plunger by a plurality ofmachine screws41 (Fig. 4). So attached to the plunger, thehead ring l0-presents ailange 42 projecting radially from the convex surface 32. The-mold box15 at its lower -portion is fitted with an insert 44 which has asmallbead 46 projecting slightly from the concave surface 21. The flange42 thus extends across the mold space 19 to engage the mat 20 and pressit rmly in sealing relation against the bead 46. To positively locatethe final position of the plunger 16 as it is shifted into the mold box15, a bolster ring 47 is connected to the lower end of the mold boxpresenting a horizontally concave surface 48 (dat in a verticaldirection) engaged by a shoulder 49 formed on the head ring 40. Thisthus precisely determines` the thickness of the mold space 19 each timethe plunger is closed, and makes successively cast plates of uniformthickness. The engagement of the surface 48 and shoulder 49 also makescertain that the flange 42 positively clamps the matrix 20 against thebead 46, yet without such pressure that the matrix is cut or otherwisedamaged. The horizontal step 50 on the bolster ring 47 serves as asupport for the lower edge of the matrix 20 and accurately determinesthe vertical position of the latter.

When curvedV stereotype printing plates are mounted on printingcylinders, it is desirable to anchor their curved edges, and for thispurpose, such curved edges are beveled, as is well known in the printingart. The upper curved edge of a printing plate (viewed as it is orientedimmediately after casting and while still in the mold box) is beveled inthe process of cutting olf the upper tail. It is highly desirable,however, to mold the beveled configuration for the lower curved edge ofthe printing plate at the time it is cast in order to eliminate afurther machining or finishing operation.

In the present instance, this is accomplished by forming the uppersurface of the head ring flange 42 with a recess 51 having one sidethereof inclined from the axis of the plunger 16. That is, the inclinedsurface of the recess 51 makes an acute angle a with a line runningparallel to the ax-is ofthe convex surface 32. As molten metal is pouredinto the mold space 19, therefore, the head ring flange 42 not onlycloses the bottom of that mold space but, due to the inclined recess 51,produces a beveled configurationV for the lower cunved edge E of the.resulting plate P. It may also be desirable to cast plates havingadifferent beveled configuration at their lower edges` and to accomplishthis result, head rings having various angles may be substituted for thering shown in the drawings.

Thehead ring 40 in the exemplary form illustrated is a solidmetal piecewhile, as previously mentioned the plungeritself is provided withinterior passages for the circulation of cooling fluids. Although heatin a large measure will be conducted from the head ring to the plungerand thusv removed by coolants circulated in the latter, it has beenfound that when a number of plates are cast in rapid succession thetemperature of the head ring may appreciably exceed that of the convexsurface 32. Underthat condition, the cast plates sometimes have atendency to-stick to the ring 40` and cannot be easily stripped orlifted from the plunger.

To obvia'te this difficulty and supplement cooling of thehead ring byheat conduction to the plunger, means are vprovided to independentlycool the head ring 40. In the preferred form shown, such supplementalcooling means take the form of a plurality of cooling ns 53 projectingfrom surfaces of the head ring 40 as best shown in Fig. 4. Thesecooling-tins facilitate heat transfer to the surrounding atmosphere sothat even during rapidly repeated plate casting the head ring remains atabout the same temperature as the convex surface 32. There is thus nodanger that the lower edge of a cast plate will be soft when the upperportion has solidied; and the plunger may. be opened soon after moltenmetal is poured-into the mold-space without likelihood that the platewill stick rto the 'head ring 4t).

In prior plate casting apparatus of this general character,thevbottomfof the mold space formed between the mold box and the plungerhas been closed by a separate head ring which was supportedindependently of the plunger and movable by a separate actuating linkagethrough a different path than that of the plunger as the latter waspulled to its .open position. This was deemed necessary in order tomove\the plunger into the mold box without having it strike the concavesurface of the latter and in order to get the beveled edge of a castplate out of the inclined recess which produced it. Fins or flashing,produced by molten metal running between the plunger and head ring oftenresulted because the seal between the two had to be broken each time theplunger was opened, and thus frequently became ineffective. Y

Through the use of the fixed head ring 40, which thus becomes anintegral part of the plunger 16, the need for a separate head ring isentirely eliminated, as well as the need for a linkage to move that headring as the plunger is opened and closed. There is no problem, in thepresent case, with creating an effective seal between the head ring andthe plunger since the bolts 41 may serve to draw the head ring tightlyagainst the plunger to create a very tight and permanent joint at 52.There is no possibility, therefore, of a lin or flashing being producedon a cast plate due to molten metal running between the head ring andthe plunger. The rm engagement of the surfaces 48, 49 on the bolsterring and head ring, respectively, produces accurate location of theplunger 16 with respect to the mold box 15. The mold space 19, andplates produced by it, are thus always of uniform thickness.

With the liange 42 of the head ring 40 projecting from the lbottom ofthe plunger 16, it might strike the mold box or mar the matrix as theplunger is moved between its open and closed positions, since the bottomend of the plunger must swing rearwardly with respect to the mid-portionof the plunger as the latter is tilted to a horizontal position. Inkeeping with another feature of the invention, this problem is obviatedby a support linkage for the plunger constructed and arranged so thattilting of the latter takes place only when it is appreciably spacedfrom the mold box. In other words, the plunger is maintainedsubstantially vertical or parallel to the mold box as it moves into orout of the latter, appreciable tilt ing of the plunger occurring onlywhen it is sufliciently spaced to permit the head ring to clear both theconcave surface 21 and the matrix 20.

As here exemplified, the plunger support linkage comprises a pair ofsupport links 60 which are generally of cruciform configuration. Asshown best in Fig. l, the links 60 are rigidly fixed on opposite sidesof the plunger 16 to the respective sliding bar brackets 34 by aplurality of bolts 61. Preferably, the holes in the links 60 throughwhich the lbolts 61 pass are elongated to permit some adjustment of eachlink longitudinally of the plunger in order that the relationshipbetween the mold box and the plunger may be initially adjusted.Projecting outwardly from each bracket 60 are integral arms 62 (Fig. 2)which join to form a bearing 64 journaling a shaft 65 which, in turn,carries a guide wheel 66. These guide wheels are peripherally grooved torest upon and roll along the guide rails 18a at the upper edges of therespective side frames 18. The guide wheels thus constitute a rollingpivot support for the plunger, since the latter may move horizontallyalong the rails yet pivot about the common axis of the two shafts 65.

For the purpose of effecting such translation of the plungerhorizontally along the rails 18a and at the same time controlling thetilting of the plunger, the brackets 60 include depending bracket arms68 which are, in effect, rigid with and form a part of the plungeritself. Extending between and journaled in the frame sides 18 at a pointbelow the plunger is a rock shaft 69. A pair of levers or drop links 70are disposed at opposite sides of the plunger 16 and connected at theiropposite ends of the rock shaft 69 and the respective bracket arms 68.The lower ends of the drop links 70 are rigidly connected, as by a keyat 71, to the rock shaft 69, while their, upper 6 ends are pivotallyconnected as by a pin 72 to the respective arms 68. As shown best inFig. 1, the links 70 are preferably formed with T-shaped inserts 73 heldin place by cap screwsY 74, the insert being apertured at 75 to receivethe pivot pin 72. By the insertion or removal of shims 76 between theend of the link 70 and the heads of the inserts 73, the effective lengthof the arms 70 may be minutely adjusted when the apparatus is assembledto produce the desired location of centers described below.

The rock shaft 69 may be turned or oscillated through an angle ofapproximately 90 by any suitable means. The size and location of theparts, however, are such that the opposite ends of the drop links 70 aresubstantially vertical, that is, the axis of the rock shaft 69 and theaxis of the pin 72 are substantially vertically alined, at the time thatthe plunger is vertical and within about one or two inches of beingfully seated in the mold box 50. This relationship of the pivot pointsis most important and is particularly illustrated by Fig. 7. With theshaft 69 rotated in a counterclockwise direction from the position shownin Fig. l, the link 70 also rocks counterclockwise so that its right endmoves upwardly and to the left in an arc around the axis of the shaft.As a result, the plunger 16 is bodily shifted to the left toward themold box, the guide wheels 66 rolling along the guide rails 18a, whilethe plunger itself pivots about the guide Wheel shafts from a horizontalposition toward a Vertical position. When the opposite ends of the linksare substantially vertically alined, for example when the links liealong the vertical line in Fig. 7, the plunger 16 will be at or near itsfully closed position. As here illustrated, the plunger is fully closedwhen in the position shown by solid lines and will be in the slightlyretracted position shown by dotted lines in that ligure. It may beobserved that as the links 70 are rocked through a small angle 0 ineither direction from the vertical position represented by the line 75,the upper end of those levers will move principally horizontally througha variable distance labeled x, and will move only a very small,substantially negligible vertical distance as above shown by thevariable dimension y. In result, therefore, the plunger 16 is notappreciably tilted or rocked about the guide wheel shafts 65 duringtravel between the two positions depicted in Fig. 7. This is mostimportant, for it makes certain that the plunger Will not tiltappreciably until it has been withdrawn from the box 15 sutciently sothat the head ring 40 clears the mold box.

The action can be demonstrated with reference to simple mathematicalexpressions. Assuming that the links 70 are initially in the verticalposition represented by the line 75, and that they have an effectiveradius R, the vertical displacement of the pin 72, represented by thesymbol y, may be expressed Similarly, the horizontal displacement of thepin 72 for a given angular dellection of the lever arms 70 from theirvertical positions may be represented by the dimension x and expressed:

x=R sin 6 As the angle 0 is increased from zero in either direction fromthe line 75, the distance x increases rapidly; While the dimension yremains very small. For example, in one physical construction of thepresent apparatus, the plunger 16 may move through a distance of about1% inches with the pivot pin 72 moving slightly less than 0.1 inch in avertical direction. This produces practically no tilting of the plungerabout the guide wheel shafts 65. As a result, the plunger is shiftedsubstantially horizontally into and out of the mold box 15 over one ortwo inches of travel as it enters and leaves the latter. Furtherretraction of the plunger, however, results in it being tilted 7 over tothe horizontal position as depicted in Figs. 9 and l0.

By so constructing the linkage for the plunger 16, several advantagesaccrue. First, the head ring 40 may be integral with the plunger 16 andyet not strike the concave surface 21 of the mold box 15 as the plungerenters or leaves the mold box. The integral head ring eliminates thepossibility 'of flashings or ns being produced by rnolten metal runningbetween the plunger and the head ring.

Direct abutment of the head ring against the mold box results inpositive positioning of the latter to accurately define the mold space19.

Due to the fact that the plunger 16 moves almost purely horizontally asit seats in or initially retracts from the mold box 15, the flange 42 onthe head ring 40 approaches and leaves the matrix substantially at rightangles to the surface of the latter. In clamping the matrix 20 againstthe bead 46V (Fig. 4), and in releasing the matrix from the bead, thehead ring 40 thus does not tend to slide along the surface of thematrix. As the plunger opens, therefore, and the matrix held in theleaves 25 lags behind, the matrix is stripped from the cast platewithout being torn, wrinkled, or otherwise damaged. The same matrix maybe used to cast several plates in succession, and without manuallyreplacing and adjusting the matrix in the mold box.

The invention includes, in combination with the rigid head ring 40 andthe advantageous linkage comprising the rock shaft 69 and levers 70, acooperating mechanism for lifting or stripping cast plates away from theplunger as the latter is moved to its open position. When the plunger isopened, and carries a cast plate with it to its horizontal position, itis desirable that the plate be elevated above the plunger so that it maybe slid directly onto adjacent ways (not shown) and into a shaving arch(not shown).

With the inclined recess 51 in the head ring 40, it is diflicult to liftthe plate P directly away from the plunger, i.e., in a directiontransverse to the axis of the convex surface 32. The beveled curved edgeE of the cast plate P would catch in the recess 51 and the plate wouldbe deformed, especially while still very hot, in being forced out ofthat recess. To obviate this difficulty, plate stripperson eitherl sideof the plunger are adapted to be shifted in a direction inclined to theaxis of the latter, and in a direction away from the head ring.

As here shown (Fig. l), plate strippers in the form of bars 80 aremovably supported on the opposite sides of the plunger 16 so that theymay be retracted when the plunger is closed and elevated both axiallyand transaxially relative to the convex surface 32 as an incident toopening of the plunger. Each of the plate stripper bars 8i) has an uppersurface 8l adapted to underlie the opposite straight edges of the plateP when the latter rests on the plunger surface 32. Serrations or teeth82 may be cut in that surface for gripping engagement with the edges ofthe plate. Each of the bars 80 includes a pair of spaced ears 84 whichare connected to the side of the plunger 16 in a manner to permit thebar to move simultaneously both radially and axially of the plungerproducing a resultant inclined movement away from the head ring 40.

In the present instance this is accomplished by the provision of angled,camming slots 85 cut in the ears 84 and receiving camming pins 86rigidly xed to the sliding bar brackets 34 which, as explained above,are fastened to the plunger itself. The upper and lower portions 85a,85b of the camming slots run in a direction which is substantiallyvertical as viewed in Fig. l, or, in other words, in a directiontransverse to the axis of the convex surface 32. The central portion 85Cof each slot 85 is, however, inclinedfrom the vertical when in theposition shown by Fig. 1 so that as the bar is shifted transversely 'tothe axis of the convex surface 32, it also moves axially of thellatterand in a direction away from the head ringr40.

In order to automatically move the plate stripper bars to the positionshown in Fig. l as an incident to movement of the plunger 16 to itshorizontal, open position, and to let the bars 80 drop away from theconvex surface 32 as the plunger is moved to its closed position, eachof the bars 80 includes a central depending leg portion 88 which isadapted to engage stationary abutments supported on the inner sides. ofthe frames 18. As shown best in Fig. 3, a pair of Aabutment brackets. 89are fixed to the respective side frames 18 and carry abutment rollers 90rotatably mounted on supporting pins 91.

As the plunger swings to its vertical position (Fig. 8), the lower edgesof the legs 88 swing away from the abutment rollers 90 so that the platestripper bars 80 drop by gravity until the camming pins 86 are in theupper ends of the slots 85. The upper surfaces 81 of the stripper bars,therefore, are retracted from the convex surface 32 and permit thesliding bars 35 to close. As the plunger 16 swings toward its horizontalposition, the lower edges of the legs 88 engage the abutment rollers 90(Fi-g. 9,) and cause the stripper bars to move upwardly, the directionof motion being guided by slots 85 and the camming pins 86. By the timethe plunger has reached its horizontal position (Fig. l0), the lowerends of the legs 88 remaining in contact with the rollers 90, thestripper bars 80 have been shifted upwardly relative to the convexsurface 32 so that the pins 86 are in the lower ends of the slots 85.The position of the roller 90 is such that the bars 80 make contact withthe plate P when the pins 86 are riding in the portion 85C of the slot85 (Fig. 9).

Withthis movement of the stripper bars 80 relative to the plunger 16,the upper edges of the bars engage the lower edges of the cast plate Pmolded on the convex surface 32 as the plunger tilts to horizontal orplate discharge position. The stripper bars, therefore, lift the castplate P bodily away from the convex surface 32, rst shifting the platein a direction inclined to the axis of the convex surface and axiallyaway from the head ring 40. That angular motion of the stripper bars,produced by the inclined slot portions 85C, corresponds generally to theangle a (Fig. 4) so that the plate P is lifted smoothly out of the headring recess 51. Following the inclined movement of the plate P producedby the cam slot portions 85c, the slot portions 85b cause continuedmovement of the stripper bars 80 and plate P in a directionsubstantially perpendicular to the axis of the convex surface 32, untilthe plate occupies the position shown in Fig. l0 when the plunger isfully open.

With the cast plate P elevated from the plunger 16 as shown in Figs. 1and l0, it may be slid onto adjacent ways (not shown) and into a shavingand cut-off machine (not shown). The latter is employed to shave theinner surface of the cast plate to a perfectly cylindrical shape, makingthe plate of uniform thickness. At the same time, the upper portion ortail of the plate is trimmed off. It is highly desirable that the castplates have a series of axially spaced circumferential ribs on theirinner cylindrical surfaces in order that the shaving operation need notremove metal from the entire surface but only from the ribs themselves.In prior practice, such ribs have been made of a relatively sharpV-shape in cross section, the included angle of the rib cross sectionbeing about 30. The convex surface of the plunger was formed with aseries of axially spaced grooves therein to mold the ribs at the time aplate was cast, the sides of the grooves making an angle of about 75with a line parallel to the axis of the plunger surface.

In the present instance, however, the completed plate P is not lifteddirectly axially away from the convex surface 32 for lthe reasons givenpreviously, i.e., the plate is shifted at an angle away from the convexsurface in order that itslower curved edge will be lifted freely out ofthe inclined recess in the head ring 40.

In accordance with another feature of the invention, provision is madeto form ribs on the inner surfaces of cast plates in a manner such thatthey permit this lifting ofthe plate in a direction inclined axially ofthe plunger. For this purpose, a plurality of circumferential grooves 95are formedin the convex surface 32, such grooves being spaced axiallyalong the plunger and shaped to have one side wall thereof angled in thegeneral direction of movement of the completed plate P as it is strippedfrom the plunger 16. As shown best in Fig. 4, each of thecircumferential grooves 95 is shaped such that the sidewall 96 remotefrom the head ring 40 is inclined at an angle from parallelism `with theaxis of the convex surface 32. The angle is preferably slightly smallerthan the angle a of the inclined surface 51 in the head ring recess. Itmay be, for example, in the order of 30, while the angle a may be in theorder of 45. The inclination of the plate stripper slot midportions 85Cmay be either the angle of the ring or the angle of the grooves but ispreferably intermediate between the angle a for the recess 51 and theangle for the side ywalls 96, i.e., the inclination of the slot portion85e is preferably between 30 and 45. With this arrangement, when theplate stripper bars 80 lift the cast plate P away from the plungersurface 32, the ribs r formed on the plate by the ,grooves 95 will slidefreely out of those grooves.

Plate casting apparatus of the type here described is often used toproduce a great number of plates in only a short time. The rush oftranslating a late-breaking news story into type and getting a newspaperon the street promptly may often require that some sixty curvedstereotype plates be made in the course of a half hour. The plunger 16is, of course, relatively heavy and manual movement of the same betweenits open and closed positions may require considerable physical efforton the part of a workman. It may result in fatigue so that the workmanbecomes careless as to other details and spoils many plates which wouldotherwise be satisfactory.

To assist the workman and eliminate fatigue, power means are employed tomove the plunger 16 between its two positions, and to positively holdthe plunger in its closed position so that entire reliance need not beplaced upon the locking action of the sliding bars 35. In keeping withone aspect of the invention, means are provided for exerting power toremove the plunger through the final portion of its closing path and to`hold it in its closed position, while the same power means are adaptedand controlled to supply all of the energy required to swing the plungerfrom its closed, vertical position to its open, horizontal position. Ithas been found highly advantageous to use only partial power closingsince this preventsthe plunger from being swung too rapidly into themold box 15. If that occurred, the inertia of the plunger might slam itinto the mold box, possibly damagingv the mold box, plunger, or the typematrix.

In the specic arrangement here illustrated, a power actuator `in theform of a double-acting pneumatic ram 100 is connected to rotate therock shaft 69. The ram 100 includes a cylinder 101 fastened to a.bracket fixed' to one of the side frames 18 (Fig. l) by a trunnionconnection, and a piston rod 102 projecting from the cylinder forpivoted connection at 104 to a radius arm 105 rigidly connected at itsopposite end to the rock shaft 69. When the piston rod 102 moves to theleft as viewed in Fig. l, the plunger is shifted to its horizontal, openposition as illustrated; on the other hand, when the piston rod 102moves to the right, it turns the rock shaft 69 counterclockwise,rotating the arm 70 so that the guide wheels 66 roll to the left and theplunger is swung to its vertical position through the linkage previouslydescribed.

Energization of the power actuator or ram 100 is controlled such that itis eective in moving the plunger 16 toward its closed position onlyafter the latter has closely approached the mold -box 15. For example,the actuator i is shifted to the right.

is controlled such that an operator must manually swing the plunger towithin about three inches of being fully closed. At that point, the ram100 is automatically energized and the piston rod 102 is shifted fullytothe right tomove Ithe plunger to its fully closed position. Thisprevents the plunger from slamming into the mold box. Conversely, theactuator 100 is energized so that it does all of the work in moving theplunger to its horizontal position. i

The foregoing is accomplished in the exemplary arrangement by employingtwo-position solenoid valves 106, 107 (Fig. ll) interconnected betweenthe ports 101er, 101b at the opposite ends of the cylinder 101, anexhaust conduit 108, and a source of air pressure 109. Since the valves106 and 107 are substantially identical, the brief description of onewill sutce for both.

' As shown in Fig. ll, the valve 106 includes a casing 110 having a rod111 axially slidable therein and biased to the left by a compressionspring 112. The casing 110 includes a rst port 113 which is straddled bysecond and third ports 114 and 115. The rod 1,11 is formed with anenlarged portion 111a which normally blocks the port 115 and a secondenlarged portion 111b which normally clears the port114 but covers Ithelatter when the rod Movement of the rod to the right also uncovers theport 115. 'Ihe ports 114, 115 are connected respectively to Ithe exhaustconduit 108 and the air pressure source 109. For the purpose of shiftingthe rod 111 to the right against the bias of the spring, a solenoidwinding 118 is located within the casing 110 in surrounding relation toan armature portion of the rod 111. That solenoid is controlled in amanner to be described below.

It will be apparent that with the rod 111 in the position shown, theport 101a at the right end of the cylinder 101 is vented to theatmosphere through the valve ports 113, 114 and the exhaust conduit 108.However, when the solenoid 118 is energized and the rod 111 shifted tothe right, the enlarged portion 111b covers the port 114 and port 115 isuncovered by the portion Illa so that air pressure is supplied throughthe valve ports 115 and 1-13 to the interior of the cylinder 101 on theright side of the piston.

The valve 107 likewise includes a casing 120 containing an axiallyshiftable plunger 121 biased to the right by a compression spring 122.In the normal position illustrated, the enlarged portion 121a of theplunger blocks communication with the air pressure source 109 so thatthe interior of the cylinder 101 on the left side of the piston isexhausted. However, when a controlling solenoid 128 is energized toshift the plunger 121 to the left, then air pressure is supplied fromthe source 109 through the casing to the interior of the cylinder 101 onthe left side of the piston, causing the piston rod 102 to move to theright.

To control the valves 106, 107 in a manner to energize the poweractuator 100 as explained above, a first limit switch LS1 is fixed tothe inner side of one of the frames 18, the switch having an actuatingplunger LSlla spring biased outwardly and depressed by a lever 130whenever a roller 131 is engaged by a pin 132 carried by one of thelevers 70 (Fig. l). The location of the limit switch LS1 and the roller131 relative to the rock shaft 69 and the arm 70 is such that the switchwill be actuated just before the plunger 16 reaches a position fullynested in the mold box 15. Preferably, the pin 132 engages the roller131 to depress the actuator LSla when the plunger 16 is about threeinches in front of the mold box 15. Another limit switch LSZ is mountedon one of the side frames 18, having an actuator LSZa spring biasedoutwardly and disposed in the path of a lever 135 carrying a roller 136.The latter is disposed in the path of a projection 138 xed to one of thesliding bar brackets 34 on the face of the plunger 16. The projection138 and roller 136 are relatively located such that the former willengage and II shiftthe latter (to actuate the switch LSZ) just as the.plunger reaches itsfully open or horizontal position as shown inFig. 1.

Limit switches LS1` and LSI-together with the solenoids 118 and128 forthe control valves 106` and 107 are connected in circuit asschematically illustrated by Fig. 12. T heA limit switch LS1k hasnormally openk contacts LSlb connectedl inseries withY the solenoid 128through normally closed contacts CRa of a control relay having a coilCR. This series connection is made across a voltage source representedby the power lines L1, L2. When the plunger is manually moved almost toits closed position, therefore, andthe limit switch LS1. is actuated toclose the. contacts.LS1b, the solenoid 128 is energized to. .shift thevalve plunger 121 so that air pressure is supplied to thev left side ofthe cylinder 101, causing the piston rodz 102'to move to the right. Thisresults in the application of a kcounterclockvvise torque to the rockshaft 69 so that the plunger 16V is moved under the iniiuence oftheactuator firmly into the mold box 15. Pneumatic pressure remainsin theleft side of the cylinder 101 holding the plunger in its closedposition; even if the locking `action of the sliding bars 35 shouldfail, therefore, the plunger 16 cannot open and spill molten metal.

When it is desired to shift the plunger 16 to its open position, theoperator depresses a normally open push button switch S. The latterswitch is connected in series across the lines L1, L2 with normallyclosed contacts LSZb of the switch LS2 and the solenoid 118 of the valve10,6. Also connected in parallel with the solenoid 118 is the relay coilCR, the latter relay also having normally open contactsCRb in parallelwith the switch S. When the switch S is depressed, therefore, the relayCR is energized immediately and seals in around the push button switch Sthrough the contacts CRb. The contacts CRa. open to de-energize thesolenoid 128, while a circuit is completed through the now closedcontacts LSZb, the now closed contacts CRb, to energize the solenoid118. The valvev 107is thus deactuated and the valve 106 actuated so thatthe left side of the cylinder is vented and the right side supplied withpressure fluid. Accordingly, the piston rod 102 moves to the left,exerting a clockwise torque on the rock shaft 69 so that the plunger 16.isrnoved out of the mold lbox 15 to its` horizontal position shown inFig. l. When the plunger reaches its horizontal position, the projection138 engages the roller 136 and actuates the limit switch LSZ, openingthe normally closed contacts LSZb. This de-energizes the solenoid 118and the relay coil CR so that the circuit is in its original condition,readyr to repeat the cycle of operation described.

We claim:

l. In apparatus for casting curved stereotype printing plates, thecombination of a stationary upright, opensided mold lbox having aconcave surface adapted to receive a type matrix, a frame extendinghorizontally from said mold box, a plunger having a convex surfaceadapted to define with said concave surface a mold space, means mountingsaid plunger on said frame to move between a vertical mold space-formingpositio-n within said box and a horizontal position facilitating removalof a cast plate, said means including av rolling pivot connectionbetween said plunger and frame and a lever pivotally connected at itsopposite ends between said frame and plunger such that its opposite endsare substantially vertically alined when the plunger is Vertical andseated in the mold box, a head ring rigidly fixed to the bottom of theplunger and presenting a flange extending radially of said convexsurface to close the bottom of the mold space, said flangek having arecess in its upper surface to shape the lower edges on cast plates, aplate lifter movably mounted on the side of said plunger to engage andsupport a cast plate, camming means between said lifter and plunger formoving the former axially ofthe latter when shifted in` a-l directiontransverse. to the. longitudinal axis. of the plunger, abutment means.onthe frame engaged by the plate lifter as the plungerV is-movedv toits. horizontal position toshift the former. transversely to thelongitudinal axis of the latter, and means defining a plurality ofcircumferential grooves in the. convex surface of said plunger with oneside of each groove angled in the direction of movement of the platelifterfrelative to theplunger.

2; In apparatus for casting curved stereotype printing plates, thecombination comprising a stationary vertical mold box, a plunger movablebetween a vertical position adjacent the mold box to define a mold spaceand a forwardly tilted position, means for supporting saidV plunger suchthat it moves substantially horizontally and transverse to thelongitudinal, vertical axis of said mold box as the former enters andleaves the latter, a head ring rigidly fixed to the lower end of saidplunger and having a recess in the upper surface thereof, a plate lifterdisposed along the side of said plunger, means for shifting said platelifter at an acute angle relative to the longitudinal axis of theplunger as an incident to movement of the latter to its tilted position,and means defining a plurality of circumferential grooves in the surfaceof said plunger, each of said grooves having one side angled in thegeneral direction of movement of said plate lifter relative to saidplunger.

3; InY apparatus for casting stereotype plates, the combinationcomprising a stationary, upright, concave mold box, ya convex plungeradapted to define with said mold box a curved mold space, a head ringrigidly fixed to the bottom of said plunger and projecting therefrom toabut the mold box and close the bottom of said mold space, means formounting said plunger to move between a lirstpositiony inV which' it isvertically disposed in mold spaceforming relation to said box and asecond position in which it is shifted forwardly from said box andhorizontally disposed to facilitate removal of cast plates, said meansincludinga pivot support for the plunger movable horizontally away fromsaid lbox and a lever pivoted to a stationary point at one end andpivoted to said plunger at the other end such that said lever pivots aresubstantially. vertically alined when said plunger is seated in saidbox, whereby the plunger does not tilt appreciably as it entersL andleaves the box so that the head ring clears the box .duringl such,movement.

4. Inl apparatus for casting stereotype plates, the combinationcomprising a stationary mold box having an upright, concave surface, aplunger having a convex surface adapted to deiine with' said concavesurface a curved mold space, a headv ring fast on the bottom of saidplunger and presenting a flange projecting from said convex surface toclose the bottom of said mold space, Isaid iiangeV having a recess inits upper surface shaped to produce a beveledendedge on cast plates,means mounting said plunger for movement between a vertical moldspace-forming position. and a forwardly tilted position, a plate liftermovably mounted on said plunger, and means for shifting said platelifter away from said head ring at an angle inclined to the axis of saidconvex surface as an incident to movement of the plunger to itstiltedvvposition, whereby cast plates are lifted away from the plungerwithout interference from said head ring.

5. In apparatus for casting curved stereotype printing plates, thecombination comprising an upright mold box havingI a concave surface, aplunger having a convex surface and movable between open and closedpositions relative to said mold box, and means for stripping a plateaway from said convex surface in a direction inclined to the axis of thelatter as an incident to movement of said plunger to its open position.

6. In apparatus for casting stereotype plates, the combinationcomprising a moldV plunger having a convex surface and movable between avertical plate-casting position and Va tiltedplate-removing position, a'head ring fast-at` thev lower end of saidplunger and projectingtransversely to the mold forming surface of the latter, said head ringhaving an inclined recess in the upper surface thereof, said recessdefining an inclined bottom for the mold space to create a beveled edgeon cast plates, a plate lifter movably mounted on said plunger, meansfor shifting said plate lifter in a direction inclined to thelongitudinal axis yof said plunger and in a direction away from saidhead ring as an incident to movement of the plunger to its tiltedposition, and said plunger having a plurality of circumferential groovesformed in its convex surface to create ribs on the undersides of castplates, each of said grooves having one of its side walls remote fromthe head ring inclined generally in the direction said plate lifter isshifted.

7. In apparatus for casting steretoype plates, the combinationcomprising a mold plunger having a convex surface, means mounting saidplunger to move between a first vertical position for the casting ofplates and a second horizontal position for the removal of cast plates,a head ring rigidly xed to the lower end of said plunger and having aflange projecting radially from said convex surface, means defining arecess in the upper surface of said ange shaped to form a beveled edgeon cast plates, means defining a plurality of axially spaced,circumferential grooves in said convex surface with the wall of eachgroove remote from said head ring inclined at an acute angle relative tothe longitudinal axis of said convex surface, a pair of plate liftingbars, a pin and slot connection between said bars and the opposite sidesof said plunger, a stationary abutment engaged by said bars as saidplunger moves to its horizontal position, said slot having an angledconfiguration to cause said bars to thereby engage and simultaneouslyshift cast plates away from said head ring in a direction longitudinallyof the plunger and transversely away from said convex surface.

8. In apparatus for casting curved stereotype printing plates, a plungerhaving a convex surface, a head ring rigid with one end of said plungerand having a flange projecting radially from said surface, there being arecess in said iiange presenting a boundary surface inclined at an acuteangle relative to the axis of said convex surface, and means defining aplurality of circumferential grooves in said convex surface each ofwhich has the side wall thereof remote from said head ring inclined atan acute angle relative to the longitudinal axis of said surface, sothat cast plates resting on the convex surface may be stripped therefromin a direction inclined at an acute angle to said axis.

9. In stereotype plate casting apparatus, the combination of an uprightmold box presenting a vertical concave surface, a plunger having aconvex surface adapted to define with said concave surface a mold space,a head ring rigidly fixed to the lower portion of said plunger andprojecting radially from said convex surface to close the bottom of saidmold space, and a frame extending horizontally from said mold box, apivot support for said plunger translatable horizontally along saidframe toward and away from said box, a shaft journaled in said frame, adrop link fast at one end to said shaft and pivoted at the other end tosaid plunger to rock the latter between vertical and horizontalpositions as it is translated into and away from said mold box, saiddrop link and shaft being so arranged that the opposite ends of theformer are substantially vertically alined and the plunger axis issubstantially vertical when said plunger seats in said box so that theformer moves substantially straight into and out of said box to avoidinterference by said head ring, a double-acting power actuator operativeon said shaft to move said plunger, means including a limit switch andmeans actuating the same when said plunger is manually moved from itshorizontal position to a position closely approaching said box forenergizing said actuator for partial power closing of the plunger andholding it in the closed position, and means for energizing saidactuator in the opposite direction to effect powered movement of theplunger from it closed to its fully open position.

10. In stereotype plate casting apparatus, the combination comprising astationary mold box having a concave surface, a plunger having a convexsurface adapted to define a mold space with said concave surface, meanssupporting said plunger for movement between a closed vertical positionwithin said mold box and a horizontal open position withdrawn from saidmold box, said supporting means including a horizontally translatablepivot support, a rock shaft, and a drop link fixed to said rock shaftand pivoted to said plunger, a double-acting pneumatic ram operativelyconnected to said rock shaft, first means for energizing said ram onlyafter said plunger has been manually shifted from its open position toeffect partial power-closing of the latter, and selectively operablesecond means for energizing said ram in the opposite direction when theplunger is in closed position to effect full power opening of thelatter, said first energizing means being maintained active to hold theplunger in closed position until said second energizing means isactuated.

11. In apparatus for casting curved stereotype printing plates, thecombination with an upright mold box having a concave surface and formedat its lower end with an inwardly projecting step presenting a verticalsurface, of a plunger having a convex surface and movable between openand closed positions relative to said mold box, a head ring rigid withthe lower end of said plunger, said head ring having a matrix-clampingflange projecting radially from said convex surface and also having avertical shoulder spaced inwardly from said ange, said shoulder beingengageable directly with said vertical step surface to accuratelydetermine the spacing between the convex and concave surfaces when theplunger is closed.

12. 'Ihe combination set forth in claim 11 and further including aplurality of cooling fins integrally formed on said head ring tofacilitate the cooling thereof by transfer of heat to the atmosphere.

References Cited in the le of this patent UNITED STATES PATENTS 989,815Scott Apr. 18, 1911 1,009,272 Wood Nov. 21, 1911 1,035,956 Furlow Aug.20, 1912 1,174,978 Harm Mar. 14, 1916 1,509,078 Henzi Sept. 16, 19241,514,801 Smith Nov. 11, 1924 1,514,802 Smith Nov. 11, 1924 1,544,570Gammeter July 7, 1925 1,569,491 Hopkins Jan. 12, 1926 1,623,991 WoodApr. 12, 1927 1,786,629 Pepper Dec. 30, 1930 1,848,593 Wood Mar. 8, 19321,957,104 Gerrard et al. May 1, 1934 2,242,943 Clark May 20, 19412,464,051 Morin Mar. 8, 1949 2,484,907 Purcell Oct. 18, 1949 2,519,739Butner Aug. 22, 1950 2,526,753 Huck Oct. 24, 1950 2,618,823 Perkon Nov.25, 1952

